This invention relates generally to storm water sewer systems, and more particularly to a drain insert adapted to prevent sediment or debris such as leaves, sand, stones, gravel and, in some cases, petroleum products, from entering into the storm water removal system.
There is increased importance being placed by cities on water treatment prior to the water entering the storm sewer system. Several treatment problems have been identified: stormwater run-off is contaminated with heavy metals and hydrocarbons which have leaked onto the streets and highways from a variety of sources, and leaves and other debris enter through the storm drain grate and clog storm basins outflows. In a typical storm water collection system, ground water from heavy rains or melted snow is collected in a storm sewer catch basin and flows into an underground sewer line. The water flows into the basin through openings in a grate on the top of the basin.
Water entering a sewer line should be free of solids. Early storm sewer filters removed solids from the water before the water flowed into the catch basin. These filters were made of a porous material and were located at or above grade level, which were readily visible. A very early version of this method simply used stacked hay bales around the periphery of the storm drain grate. The filters were typically placed horizontally on the top of the grate or, like the hay bales, stood up vertically in a circle above grade level, surrounding the grate. Water flowed freely through the filter and into the catch basin. Solids were captured by the filter. Over time, the solids built up on the filter, thereby impeding the free flow of water through the filter. As a result, the collected water flooded the area surrounding the storm sewer.
More modem catch basin inserts have been developed that can be installed below grade so that the solids are filtered from water without impeding the flow of water through the catch basin and into the sewer. Additionally, such filters were designed to be readily removed from the catch basin for dumping when filled with sediment and debris. Some examples of these types of filters are U.S. Pat. No. 5,575,925 (Logue, Jr.), and U.S. Pat. No. 6,086,758 (Schilling et al.), U.S. Pat. No. 6,093,314 (Wilson et al.), U.S. Pat. No. 6,059,964 (Strawser), and U.S. Pat. No. 6,045,691 (McDermott). These designs, while an improvement over the above-ground filters, suffer from several drawbacks. The Logue design, for instance comprises a filter bag with flaps that extend out from the periphery of the grate so that the grate anchors the filter bag within the catch basin. When the grate is lifted, however, the bag is subject to slide into the catch basin. The remaining prior art uses rigid frames that are adapted to fit a specifically sized drain opening and were thus not easily adaptable to differently sized or shaped openings.
Accordingly, the need remains for a drain filter insert that addresses these drawbacks in the prior art.